The pneumatic tire is a known solution for compliance, comfort, mass, and rolling resistance. The pneumatic tire has disadvantages, however, in complexity, the need for maintenance, and susceptibility to damage. A device that improves on pneumatic tire performance could, for example, provide more compliance, better control of stiffness, lower maintenance requirements, and resistance to damage.
Conventional solid tires, spring tires, and cushion tires, although lacking the need for maintenance and the susceptibility to damage of pneumatic tires, unfortunately lack its performance advantages. In particular, solid and cushion tires typically include a solid rim surrounded by a resilient material layer. These tires rely on compression of the ground-contacting portion of the resilient layer directly under the load for load support. These types of tires can be heavy and stiff and lack the shock absorbing capability of pneumatic tires.
Other non-pneumatic constructions and their benefits are described in e.g., U.S. Pat. Nos. 6,769,465; 6,994,134; 7,013,939; and 7,201,194. Some non-pneumatic tire constructions propose incorporating a shear band, embodiments of which are described in e.g., U.S. Pat. Nos. 6,769,465 and 7,201,194, which are incorporated herein by reference. Such non-pneumatic tires provide advantages in tire performance without relying upon a gas inflation pressure for support of the loads applied to the tire.
In one example of a non-pneumatic tire, a compliant band with a ground contacting portion can be connected with a plurality of web elements extending radially from a center element or hub. The hub is constructed of metal, which must be machined or cast. Unfortunately, the hub can be a substantial part of the overall cost of the non-pneumatic tire.
In addition, the metal hub can present certain performance problems. For example, in the operation of both pneumatic and non-pneumatic tires, the tire may experience an impact event that can cause permanent damage. Such an event may occur when e.g., the tire encounters a curb or other large obstacle at an excessive speed. For the non-pneumatic construction as described above, the metal hub may be permanently deformed. In turn, such deformation can cause a noticeable first harmonic non-uniformity that can be sensed by the driver of the vehicle.
The metal hub can also be susceptible to transmitting vibrations that generate undesirable noises both inside and outside of the vehicle. The high modulus of the metal structure may more readily transmit vibrations caused by factors such as e.g., asperities in the road or vibrations generated by certain components of the tire during operation.
Accordingly, a non-pneumatic tire with an improved construction would be useful. More particularly, a non-pneumatic tire that can reduce the cost of construction would be beneficial. A non-pneumatic tire that can reduce or eliminate the susceptibility to certain permanent deformations from an impact event would be advantageous. A non-pneumatic tire that can reduce or eliminate the transmission of certain undesirable vibrations to the vehicle and/or otherwise reduce noise generation would also be useful.